KIT and gastrointestinal stromal tumor: Recently, miRNA-221 and miRNA-222, whose chemical modifications affected the proliferation of imatinib-resistant GIST cells (Durso et al., 2016), were found to target KIT and promoted apoptosis of GIST cells through the KIT/AKT pathway during the imatinib resistance (Gits et al., 2013; Ihle et al., 2015).